[Michlib-l] Average Annual Snowfall for Detroit Area?

Okay, I feel like a dunce. I browsed NOAA for a good two hours yesterday, and I am either looking in the wrong place, or it simply is not there. I'm looking for a chart of the average snowfall for Michigan for the past 20 years or so. I thought NOAA would be the go-to place, but I'm not having much luck. Any help greatly appreciated! Sylvia